Answer:
1a) x=40°
2a) x=30°
Explanation:
Use the fact that the sum of the angles of a triangle is always 180°.
So for 1a), x + x+40 + x+20 = 180
Simplify to
3x + 60 = 180
3x = 120
x = 40
apply the same logic to all the others.
For circles, the sum of the angles is 360°, so for 2b)
5x+3x+4x = 360 =>
12x = 360
x = 30°